1. Field of the Invention
The present invention relates generally to the field of interactive television systems and, more particularly, to a system and method for cable operator control over enhanced programming.
2. Description of Related Background Art
Traditionally, the term “broadcasting” relates to the electromagnetic transmission of content by radio and television stations. However, with the development of cable and satellite networks, as well as the Internet, the meaning of the term has expanded to include the distribution of any type of media to multiple recipients using any transport method. For example, content is now being broadcast via packet switched networks, telephone networks, and the like.
In order to broadcast television programming from the television station to the viewer, the broadcaster divides the content of the program into video streams. Video streams for a television broadcast typically include a sequence of video frames or images that combine to form a moving image. Each video frame is referred to as a raster and includes a plurality of scan lines transmitted and displayed sequentially. Video streams can be either analog or digital.
Traditionally, television sets have displayed only analog video streams. However, digital televisions and digital video broadcasting techniques are growing in popularity. For example, television and radio broadcasts are currently being sent over both analog and digital systems using terrestrial, cable, satellite, and packet switched networks. (e.g., the Internet)
Gradually, broadcast television and Internet technologies are beginning to converge. Specifically, access to the World Wide Web via Internet-enabled television systems is growing in popularity, particularly as the convergence allows television viewers to access enhanced content. Enhanced content may include, for example, additional information about the television broadcast, related Internet website links, images, streaming video, e-commerce opportunities, and the like.
Enhanced content may be encoded within analog video streams. For example, cathode ray tubes (CRTs), as used in nearly all televisions and computer monitors, require a small amount of time for the scanning circuitry to return to the top of the screen after displaying the last line at the bottom of the screen. Video signal standards recognize this fact by inserting a number of “blank” lines at the beginning of each new video frame, which form a vertical blanking interval (VBI). During the VBI, the need to transmit video frame information is suspended and enhanced content may be encoded into the video stream.
Similarly, enhanced content may be encoded within digital video streams. With the development of various encoding algorithms, such as MPEG (Motion Picture Experts Group), digital video streams may be transmitted to, and displayed on, a variety of devices. Digital broadcasting algorithms typically divide the video stream into a sequence of data elements called “packets.” Each packet typically includes a header, which may be used to store information about the packet or the program to which it pertains. Generally a number of additional enhanced content packets can be added to the video stream without adversely affecting the quality of the digital broadcast.
Additionally, the Advanced Television Enhancement Forum (ATVEF) standard provides a mechanism for delivering interactive television experiences of enhanced content to a variety of television, set-top, and PC-based receivers. The ATVEF standard delivers enhanced content by embedding “triggers” into a television broadcast. Triggers allow content developers, broadcasters, or cable operators to insert real-time prompts into the video stream when enhanced content is available to the viewer. Among other information, a trigger may contain a network address, such as a Universal Resource Locator (URL), that defines the location of the enhanced content. Other optional information often included in a trigger include a human-readable name, an expiration date, and a script.
ATVEF enhanced content referenced by a trigger may reside on the Internet, another public network, or a private network. ATVEF triggers are typically text-based and follow the basic syntax format of the EIA-76A standard, but may also be transported via EIA-608, multicast IP packets, or other transport systems.
As previously mentioned, enhanced content developers or network broadcasters may deliver enhanced content by embedding triggers into the broadcast. Conventionally, these embedded triggers pass through the cable system unchanged to be received by customers of the cable operator.
Unfortunately, conventional systems do not allow cable operators to block, append, filter, or simply replace triggers embedded in a television broadcast. From the cable operator's perspective, this is problematic because triggers, like advertisements, have monetary value to the cable operator. Additionally, since triggers may actually annoy viewers with irrelevant links, providing cable operators with control over triggers may increase viewer satisfaction with the cable service. Moreover, triggers are typically not customized to individual viewers, but are broadcast to all of the viewers receiving a particular television program. As such, many trigger links are never activated and consume valuable bandwidth that might be put to a more a productive use.
Accordingly, what is needed is a technique for providing a cable operator with control over enhanced content during a television broadcast. In particular, what is needed is a system and method for allowing a cable operator to block, append, filter, or replace embedded triggers in a television broadcast passing through the cable system.